1. Field of the Invention
This invention relates to a semiconductor sample suitable for a transmission electron microscope (hereinafter called simply xe2x80x9cTEMxe2x80x9d), which is to be observed by the TEM and a method of manufacturing the semiconductor sample.
2. Description of the Related Art
It is of importance to recognize in detail the state of distribution of impurities in an impurity diffusion region for semiconductor devices like MOS transistors incorporated into a semiconductor substrate as components of a semiconductor integrated circuit in order to evaluate and analyze the semiconductor integrated circuit.
A TEM is known as one of means for observing the impurity diffusion region, etc. in such a semiconductor substrate.
In order to observe a semiconductor by the TEM, a thin-film portion for allowing an electron beam to pass therethrough is formed in the semiconductor to be observed. The thin-film portion is formed at an edge portion of the semiconductor by beam-based grinding processing using a focused ion beam device (hereinafter called simply as xe2x80x9cFIBxe2x80x9d), for example.
Prior to the observation of the thin-film portion by the TEM, the entire semiconductor including the surface of the thin-film portion is subjected to a selective etching process using an etchant. The selective etching process makes it possible to selectively remove a lattice defective portion produced due to impurities in the thin-film portion, etc., whereby an impurity distribution can be observed by the TEM for the first time.
Meanwhile, according to the above-described conventional method of manufacturing the sample, the thin-film portion formed integrally with the edge portion of the semiconductor at the edge portion thereof is provided in continuation with a main body of the semiconductor in a region excluding the edge portion. Therefore, since a large stress is concentrated on the thin-film portion when the entire semiconductor including the thin-film portion is subjected to the selective etching process, bending distortion has occurred in the thin-film portion due to the stress.
The bending distortion of the thin-film portion results in the creation of stripe-like contrast in an image observed by the TEM, thus causing a hindrance to a good-quality TEM image.
Thus, an object of the present invention is to provide a semiconductor sample free from the introduction of bending distortion into a thin-film portion owing to selective etching corresponding to pre-treatment, and a method of manufacturing the semiconductor sample.
According to one aspect of this invention, there is provided a semiconductor sample manufacturing method, comprising the following steps of:
forming a thin-film portion for allowing electrons produced from a transmission electron microscope to pass therethrough at a portion to be observed of a semiconductor;
thereafter subjecting the thin-film portion to a predetermined etching process thereby to manufacture a semiconductor sample for the transmission electron microscope; and
defining grooves for reducing a stress introduced into the thin-film portion by the etching process in the thin-film portion prior to the execution of the etching process.
According to the present invention, even if the conventional stress is produced in the semiconductor including the thin-film portion by the etching process, the grooves defined in the thin-film portion substantially absorb a stress that acts on the thin-film portion. Therefore, the conventional concentration of stress on the thin-film portion is prevented from occurring, so that the thin-film portion is prevented from being deformed due to the stress concentration.
Typical ones of various inventions of the present application have been shown in brief. However, the various inventions of the present application and specific configurations of these inventions will be understood from the following description.